Test 2 Key - Page 0 Lab Section # Sn EEEE W— The...

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Unformatted text preview: Page 0 Lab Section # Sn EEEE W— The University of Arizona Lab TA Name Chem 152 Summer 2009 Andrew J. Grail, PhD EXAM No. 2 THE FOLLOWING MUST BE COM ETELY FILLED-IN OR YOUR EXAM WILL NOT BE GRADED. A NAME: PRINT (clearly) {aw THERE IS A 3-POINT PENALTY FOR/ILLEGIBLE NAMES or improper Scantron information. DIRECTIONS: 6DO NOT OPEN THE EXAM UNTIL INSTRUCTED TO DO SO. oYOU MUST USE PENCILS ON THE SCANTRONS oON YOUR SCANTRON m WRITE AND BUBBLE IN YOUR STUDENT ID STARTING ON THE LEFT — FOR THE ‘S’ AT THE BEGINNING, BUBBLE IN A ZERO — QON YOUR SCANTRON — WRITE AND BUBBLE IN YOUR LAST AND FIRST NAMES SEPARATED BY A SPACE OFILL IN THE CORRESPONDING FORM LETTER—~A or B eKEEP ALL PAPERS IN FRONT OF YOU, ON YOUR DESK AT ALL TIMES. oCROSS OUT ANY SCRAP WORK THAT YOU DO NOT WANT INCLUDED IN YOUR ANSWERS. eFOR MULTIPLE CHOICE QUESTIONS, BUBBLE IN THE LETTER ON YOUR SCANTRON OF THE CHOICE THAT BEST ANSWERS THE QUESTION. UNLESS NOTED THERE IS ONLY ONE CORRECT CHOICE. IF MORE THAN ONE CHOICE IS SELECTED THE QUESTION WILL BE MARKED WRONG. SELECT THE CLOSEST NUMERICAL ANSWERS IF YOUR CALCULATION . IS SLIGHTLY DIFFERENT. . . ' OFOR QUESTIONS MARKED “FREE ANSWER” or PARTIAL CREDIT —— INCLUDE ALL YOUR CALCULATIONS. IF YOU GIVE ONLY THE CALCULATED ANSWER, IT WILL BE GRADED AS ZERO CREDIT. OPOINT ALLOCATION FOR EACH QUESTION IS INDICATED. oGIVE ANSWERS FOR CALCULATIONS TO THE CORRECT NUMBER OF SIGNIFICANT FIGURES fiWHEN YOU HAVE FINISHED PUT THE SCANTRON SHEET INSIDE THE BOOKLET BEFORE HANDING IT 1N. oHOLD YOUR PICTURE ID UP TO YOUR FACE WHEN TURNING IN AN EXAM My signature below certifies that I have used a calculator for rnu-nerical calculations only and that I have not done anything unethical while taking this exam. I have read and understand the i directions NAME—— SIGN DO NOT WRITE IN THIS BOX 9) /15 10) [15 11) /IS 12) IIS 13) TOTAL (free answer) TOTAL (scantron) Page 1 Multiple Choice ~— Choose the BEST answer to each question and bubble it in on the scantron. Each probiem is worth 3 points. 1. Which of the foilowing will NOT cause a shift in the chemical equilibrium 2A(g) + Btg) “vi C(g) + mg)? A) change in temperature B) addition of a reactant C) removal of a product D) addition of a catalyst E) decreasing the container volume 2. Given: Sn02(s) + 2H2(g) :3 Sn(s) + 2H20(g) Kc = 8.12 Hz + C02(g) ‘1‘ + H20(g) Kc = 0.771 i What is the value of KC for the following reaction at the same temperature? Sn02(s) + 2C0(g) "F"— Sn(s) + 2C02(g) A) 6.26 B) 10.5 C) 13.7 D) 0.0950 E) 9.25 3. Which is not a conjugate acid-base pair? A) H2804, 5042' B) N2H4, mus+ C) on‘, H20 ’ D) ail are conjugate acid-base pairs E) none are conjugate acid-base pairs 4. The value of Kw is 2.4 x 10'14 at 37 °C. What is the pH of a neutrai solution at this temperature? A) 7.00 B) 2.40 C) 13.62 D) 6.81 E) 7.19 5. Consider the following reaction at equilibrium. What effect will decreasing the temperature have on the system? : CH4(g) + 202(g) fi C02(g) + 211206) A H° = —890 k} A) The reaction wilt shift to the left in the direction of reactants. B) The equiiibrium constant will decrease. C) The equilibrium constant will increase. D) A and B are correct E) No effect will be observed. 6. A solution of barium acetate, Ba(C2H302)2, would be A) acidic B) basic C) neutral ii) Page 2 7. Which substance wouid you expect to be the weakest acid? A) i B) i C) i H c: F \C/C\O/“ \C/C\O/” \C/C\O/H / / / H \ c: \ F \ H CI F D) H O H )C/ \H H—£——N-—H H H l l 8. Consider the following reaction at equilibrium. What effect will adding some C have on the system? C02(g) + C(s,grapi1ite) "x": 2C0(g) A) No effect will be observed. B) The equilibrium constant will decrease. C) The reaction will shift to the left in the direction of reactants. D) The equilibrium constant will increase. E) The reaction wili shift to the right in the direction of products. Free answer — Answer the question completely - Show your work! Partial credit may be given. PUT YOUR ANSWERS {N THE BOXES WHEN PRESENT. 9. Iodine monobromide, IBr, occurs as brownish-black crystals that vaporize with decomposition: 21Br(g) #- Iz(g) + Brz(g) The equilibrium constant KC at 100°C is 0.026. a) Write the equilibrium constant expression for this reaction. 5 pts b) If 0.010 mol IBr is piaced in a 1.0 L vessel at 100°C, what is the concentration (M) of [Br when the system has reached equilibrium? 10 pts 10. Find the pH of each of £he following at 25"C: a) 0.035 M HCIO2 8 pts “7* 11. Find the pH of each of the following at 25°C: 2 a, a) 0.00st cmst 3 pts “La-a 3 $7 QM”; f W95 b) 0.15MKF 7913 if“ 5, 2f Page 4 12. Hydrogen and carbon dioxide react at a high temperature to give water and carbon monoxide. KC 2 1.6 at 986°C. H2(g) + C02(g) 70+" 1120(3) + (30%} Suppose the reaction is begun with 0.250 M H2, 0.250 M C02, 0.500 M H20(g), and 0.500 M C0. 3) In which direction must the reaction proceed in order to reach equiiibrium? (snow YOUR woman 5 pts _ f {a $332”. gefi> ( 9 31:2)5 . QeQE O? b) What is the equilibrium concentration (M) of C0(g)? 10 pts Q giggie {ges- 557$ (,§§@%§ g 3.2%??? .Eifisxei ,fwe‘t .fi’éewfi w - “Q 3;: 5. age 7 , , .. ,5fi53w>€$ .B/éQ we ffleéflia’ 13) CIRCLE the stron est acid and CIRCLE the redominant factor that determines this. 8 pts Predominant Factor Electronegativity aring atom B 1; _of 47:.- Resonanc? ilization Inductive effect Eicctronegativity of H bearing atom Size of anion Resonance Stabilization lectronegativity ofHE‘éwaaifiévfito - MEWS? ' Resonance Stabilization Inductive effect Electronegativity of H bearing atom _ _ 7 sace Stiiizati Infi‘f’i‘efi HN02 VS®O3 Acid Dissociation Constants at 25°C: §€bmp0unfi éHCid; W W 4 @EMI—sweund liféfiCCI—IgCOOH g HCOBE.-- .- }. [CH3C66HWWWi1.8 x 10'5 EEEQCOOH [FQCHCOOH {F3CCOOH CICHzcaéfiwwmwmfififlcfiHQH “WW 1 ClgCHCOOH 3.3 x 10‘2 [Elgccoopl 33115363 H T332 T63, Eféfififéfifim[1”?me? iHZSe 2.0x10'4,1.0x10””lp-CIC5H4COOH 103(10‘”4 ; Z3 x lo'amw" {EaNozcgfiEBMSITEEL x 10-4“ 4.9 x 10~10 EJ—N02C6H4COOH 332"”'i“0'4} 35.2 x 10‘3 {6.0 x 10'2 [EB-x 10.1%“ "mm [C6H50H E E , 4 E .. iLO . [p—FC6H4COOH €57 x 10'8, 1.2"); 10‘” {ofE'iEEHmOOH 2.5 x 1033761“???HN02C6H4COOH {77.0 x 10‘3 gm 10”, 4.33? 10"1 {fi-CHfififiéfifimfim x 10"5 3793': 102, 6.4 x 10-5 p-CH302C6H4COOH 3.4 x 10'5 37.5 x 10-3, 6.2 x 10“, p—HZNCLH4CVOOHW [i .2 x 10'5 ‘ 5.2 x 10'[3 [CZHSSH I25 x 10"“ — {Compoumi K. 1.5 x 103, 2.0 x 10-6 ErCHZCOOwa" "1.4 x 10'3 x E04 ICHgbOOHW 7.6x10'4 [5&3CH2C00H 1.3)(10'5 {(36HSCOOH {0-C6H4(COOH) 2 1'3 x 10‘3T§§‘"ff()75 131630 {m-N02C6H4OH EEO” 2.0 x if)?“ M {fifiNozcfiHmH 7.0 x 10'8 Page 5 Page 6 Base Dissociation Constants at 25 c’C: §€ampmmfi 1K1, iQampeunffi 3K1. INHg 1.8x 10'5 3061451411; ' "13.8 x 101"; 1321076 [chg'I'x'I'éfiQSQ‘m 1.0 5:10;“ §H2N0H ' [1.1711045 go—FC6H1NH2 0.611 10-“; (5mm . “.1155; 3.6.5.- Hfidéfimfig.-- is. .16.]? (chSW' 14.0 x 10“ ip—FC6H4NH2” 14.5 x 107°; (C2H5hNH 1'3 X 108 19‘N02C6H4NH2 10514} 113514151121? 3.6"}; 10‘4 '18.;1402'0684118225 x 10'E2 @flfigmg 2.011105 {p—CH3C5H4NH2 1.011109 _‘(C2H5)3P .376w £2153“ fp-CH3OC6H4NH2 2.2 x 10Tijw -1. (C2H5)3As [376121019 1355-10011: 1.4 x 10" E Periodic Table PfiffiqEJEETEEEVWE E”REEF"E4”"'§'44’”"9?“ 2 E He = 4.003 H 1.008 g .3... ,....___..£..._._._ .______.__-._.W.21,222-..- 1.11 gm“; __- 2 Li Be B C 10.81 12.01 7 8 9 110“ N 0 EF Ne 16.00 19.00 20.18 3 .WWM .......... .1 M m... 1 i i . E i E E f I 11 12 g 313 34 315 E16 12W 18 13 Na M95 A1 ISi 1P 5 (:1 {Ar 1 22.99 24.31% 25.98 1280913097 32.07 35.45.39.953 1 I i ! 14.01 M34135 36“ Se “Br 78.96 79.90 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Kr 39.10 40.08 44.96 47.88 50.94 52.00 €54.94 ’“MWW "33"” E???” 43”“ ‘4‘?“ 42 5 R!) Sr Y Zr Nb Mo 85.473162 88.91 91.22 923195.94 19 20 21 22 "23 W24 25 25 £27 fiwfg‘ 33.4.31 35.” 1m.-. 55.85 58.93 58.69 63.55 65.39 59.72 72.61 74.92 83.80 45 47 48 49 50 “51 52 ‘53 54 E Ru th Pd gAg Cd I111 Sn Sb Te I Xe 101.1;1023 106.4;1073 112.4%:14.8§128.?§121.8 127.6 12632313 5 43 T1: (98) 44 1'45 ‘ "55 458153 22* [73 E74 75 15 CS Ba 3L3 Hf Ta W Re E 132.9 132311389 178.5 180.9 183.9 186.2 E E E E 75 b72178 179 80 81 HMEEB 84 85 86 OS in Pt lAu Hg Tl Pb Bi Po At Rn 1902:1922 195.1 197.0 200820442072 209.0 (209) E(210) :(2221 w,..................2..1.1 22111 2212M 111 112 . .22.". . wmwww. w, 87 88 89** 204 109' 59 311 Hs Mt 1 Fr Ra Ac Rf Db E (22.3.) €259.22” {251) 1262129353} (26.321592499915269) (3333 (277)? Equations: x = :iJ-S___ “172—405 217 ...
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Test 2 Key - Page 0 Lab Section # Sn EEEE W— The...

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